Appendix
A
­
Page
1
of
6
APPENDIX
A
STANDARD
METHODS
USED
FOR
CALCULATING
OCCUPATIONAL
EXPOSURES
TO
MCPB
Appendix
A
­
Page
2
of
6
A.
Introduction
This
document
is
a
summary
of
the
methods
used
to
calculate
occupational
exposures
to
MCPB.
These
methods
and
a
basic
description
of
how
they
are
used
were
taken
from
References
A
and
B.
These
references
also
contain
more
detailed
information
on
the
rationale
behind
these
methods.
Only
those
methods
that
are
pertinent
to
MCPB
exposures
are
discussed
in
this
document.

B.
Occupational
Handler/
Applicator
Exposures
Exposure
Data
Sources
The
occupational
handler/
applicator
exposures
are
calculated
using
unit
exposure
data
from
the
Pesticide
Handlers
Exposure
Database
(
PHED).
PHED
was
designed
by
a
task
force
of
representatives
from
the
US
EPA,
Health
Canada,
the
California
Department
of
Pesticide
Regulation,
and
member
companies
of
the
American
Crop
Protection
Association.
PHED
is
a
software
system
consisting
of
two
parts
B
a
database
of
measured
exposure
values
for
workers
involved
in
the
handling
of
pesticides
under
actual
field
conditions
and
a
set
of
computer
algorithms
used
to
subset
and
statistically
summarize
the
selected
data.
Currently,
the
database
contains
values
for
over
1,700
monitored
individuals
(
i.
e.,
replicates).
The
distribution
of
exposure
values
for
each
body
part
(
e.
g.,
chest,
upper
arm)
is
categorized
as
normal,
lognormal,
or
"
other"
(
i.
e.,
neither
normal
nor
lognormal).
A
central
tendency
value
is
then
selected
from
the
distribution
of
the
exposure
values
for
each
body
part.
These
values
are
the
arithmetic
mean
for
normal
distributions,
the
geometric
mean
for
lognormal
distributions,
and
the
median
for
all
"
other"
distributions.
Once
selected,
the
central
tendency
values
for
each
body
part
are
composited
into
a
"
best
fit"
exposure
value
representing
the
entire
body.

The
unit
exposure
values
calculated
by
PHED
generally
range
from
the
geometric
mean
to
the
median
of
the
selected
data
set.
To
add
consistency
and
quality
control
to
the
values
produced
from
this
system,
the
PHED
Task
Force
has
evaluated
all
data
within
the
system
and
has
developed
a
set
of
grading
criteria
to
characterize
the
quality
of
the
original
study
data.
The
assessment
of
data
quality
is
based
upon
the
number
of
observations
and
the
available
quality
control
data.
While
data
from
PHED
provide
the
best
available
information
on
handler
exposures,
it
should
be
noted
that
some
aspects
of
the
included
studies
(
e.
g.,
duration,
acres
treated,
pounds
of
active
ingredient
handled)
may
not
accurately
represent
labeled
uses
in
all
cases.
HED
has
developed
a
series
of
tables
of
standard
unit
exposures
for
many
occupational
scenarios
that
can
be
used
to
ensure
consistency
in
exposure
assessments.

The
unit
exposure
values
that
were
used
for
MCPB
are
listed
in
Table
1.
Appendix
A
­
Page
3
of
6
Handler
Exposure
Algorithms
The
basic
rationale
for
the
handler
exposure
algorithms
is
that
the
daily
exposure
is
the
product
of
the
amount
of
active
ingredient
(
a.
i.)
handled
per
day
times
a
unit
exposure
value.
The
amount
of
ai
handled
per
day
is
the
product
of
the
application
rate
times
the
area
treated.
For
example,
if
0.5
lb/
acre
of
MCPB
were
applied
to
200
acres
in
one
day,
the
amount
of
MCPB
handled
that
day
would
be
100
lbs.
The
unit
exposure
value
is
the
amount
of
exposure
that
results
from
handling
a
given
amount
of
active
ingredient
by
a
certain
method
while
using
certain
PPE.
For
example,
the
dermal
unit
exposure
value
for
open
mixing
and
loading
of
liquids
with
only
minimal
PPE
is
2.9
mg
per
pound
of
ai
handled.
In
this
example,
the
daily
exposure
would
be
100
lbs
ai
handled
times
2.9
mg
unit
exposure
per
pound
of
ai
handled
which
equals
290
mg
per
day.

Daily
dermal
exposure
is
calculated:

Daily
dermal
exposure
=
Unit
exposure
x
Application
rate
x
Area
Treated
(
mg/
day)
(
mg/
lb
ai)
(
lb
ai/
acre)
(
acres/
day)

Where:

Unit
exposure
=
normalized
exposure
value
(
mg
exposure
per
pound
ai
handled)
derived
from
chemical
specific
study
data
or
from
the
PHED
Surrogate
Exposure
Table
in
Reference
A.
Application
rate
=
normalized
application
rate
based
on
a
logical
unit
treatment
such
as
acres,
a
maximum
value
is
generally
used
(
lb
ai/
acre);
and
Area
treated
=
normalized
application
area
such
as
acres/
day.

Inhalation
exposures
are
calculated
in
a
similar
manner
using
inhalation
unit
exposure
values.
The
inhalation
unit
exposure
values
(
ug/
lb
ai)
as
presented
in
the
PHED
surrogate
exposure
tables
were
based
on
a
human
inhalation
rate
of
29
L/
minute
and
an
8­
hour
working
day.

Daily
inhalation
exposure
is
calculated:

Daily
inhalation
exposure
=
[
Unit
exposure
x
Application
rate
x
Area
Treated]
X
(
1000
ug/
1
mg)

(
mg/
day)

Where:
Unit
exposure
=
normalized
exposure
value
(

g/
lb
ai
handled)
derived
from
study
data
or
PHED;
Application
rate
=
same
as
for
dermal
exposure
(
lb
ai/
acre);
and
Area
treated
=
same
as
for
dermal
exposure
(
acres/
day).
Appendix
A
­
Page
4
of
6
The
daily
absorbed
dermal
dose
(
mg/
kg
BW)
is
calculated
from
the
dermal
exposure
by
dividing
the
result
by
the
body
weight
(
70
kg).
In
the
example
above,
the
daily
dermal
dose
would
be
(
290
mg/
day)/
70
kg
which
would
equal
4.1
mg/
kg/
day.
The
same
algorithim
is
used
for
calculating
inhalation
doses
and
the
standard
adsorption
factor
of
1.0
is
used.
A
body
weight
of
70
kg
(
average
adult
body
weight)
is
used
for
both
dermal
and
inhalation
exposures
because
the
effects
observed
in
the
toxicology
studies
were
not
gender
specific.
It
should
also
be
noted
that
a
dermal
absorption
factor
of
1.0
is
used
for
MCPB
because
the
dermal
endpoint
is
from
a
dermal
toxicity
study.

Absorbed
Daily
Dose
is
calculated:

Absorbed
daily
dermal
or
inhalation
dose
=
(
Daily
dermal
or
inhalation
exposure
x
absorption
factor)
/
body
weight
(
mg/
kg/
day)
(
mg/
day)
(
unitless)
(
kg)

[
Note:
an
absorption
factor
of
1.0
was
used
for
dermal
exposures
and
1.0
for
inhalation
exposures.]

Because
MCPB
exposures
from
the
dermal
and
inhalation
routes
do
not
have
the
same
toxicological
effects,
the
dermal
and
inhalation
Margin
of
Exposure
(
MOEs)
were
calculated
separately.

Margin
of
Exposure
is
calculated:

MOE
(
unitless)
=
NOAEL
(
mg/
kg/
day)
/
Dose
(
mg/
kg/
day)

The
target
MOEs
are
100
for
both
dermal
and
inhalation
exposures
for
occupational
handlers.
Scenarios
with
MOEs
greater
than
the
target
MOEs
do
not
exceed
the
Agency's
level
of
concern
for
the
occupational
population.

C.
Post­
Application
Occupational
Exposures
The
algorithms
used
to
estimate
daily
dermal
dose
and
the
MOE
for
the
dermal
postapplication
scenarios
are
similar
to
those
described
above
for
the
handler/
applicator
scenarios.
The
only
major
difference
is
that
the
daily
dermal
exposure
is
calculated
by
multiplying
the
dislodgeable
foliar
residue
level
(
ug/
cm2
of
leaf
area)
times
a
transfer
coefficient
(
amount
of
leaf
area
contacted
per
hour
for
a
given
activity).
Inhalation
exposures
are
not
calculated
for
the
postapplication
scenarios
because
inhalation
exposures
have
been
shown
to
account
for
a
negligible
percentage
of
the
overall
body
burden.
This
is
particularly
true
for
MCPB
which
has
a
very
low
vapor
pressure.

The
following
equation
taken
from
Reference
B
is
used
to
calculate
dermal
doses
for
MCPB
on
each
post­
application
exposure
day
after
application.
Appendix
A
­
Page
5
of
6
Post­
Application
Dermal
Exposure
is
calculated:

Dermal
exposure
(
mg/
day)
=
(
DFR
at
day
t)
x
CF1
x
TC
x
#
hours/
day
)

Where:

DFR
=
dislodgeable
foliar
residue
(
ug/
cm2)
at
day
(
t)
after
application
CF1
=
conversion
factor
to
convert
DFR
value
in
ug/
cm2
to
mg/
cm2
TC
=
transfer
coefficient
(
cm2/
hour)
Hours/
day
=
standard
assumption
is
8
hours
exposure
per
day
Once
the
post­
application
dermal
exposures
are
calculated,
the
dermal
doses
and
MOEs
are
calculated
in
the
similar
manner
as
described
for
handlers.
The
single
difference
is
that
only
the
dermal
route
of
exposure
is
considered.
The
target
MOE
is
100
for
occupational
exposures.

Absorbed
Daily
Dose
is
calculated:

Absorbed
daily
dose
(
mg/
kg/
day)
=
(
daily
dermal
exposure
(
mg/
day)
x
dermal
absorption
factor)
/
BW
(
kg)

[
Note:
a
dermal
absorption
factor
of
1.0
was
used
for
MCPB]

Margin
of
Exposure
is
calculated:

MOE
(
unitless)
=
NOAEL
(
mg/
kg/
day)
/
Absorbed
Daily
Dose
(
mg/
kg/
day)

References
(
A)
PHED
Surrogate
Exposure
Guide,
V1.1.
Health
Effects
Division,
Office
of
Pesticide
Program.
August,
1998.

(
B)
Series
875
­
Occupational
and
Residential
Exposure
Test
Guidelines,
Group
B
­
Post
Application
Exposure
Monitoring
Test
Guidelines.
U.
S.
EPA.
February
10,
1998.
Appendix
A
­
Page
6
of
6
Table
1:
PHED
Exposure
Data
Used
for
MCPB
Exposure
Scenario
Baseline1
Dermal
(
mg/
lb
ai)
Baseline1
Inhalation
(
ug/
lb
ai)
Single
Layer1
Dermal
(
mg/
lb
ai)
Comments2
Mix/
Load
Liquid
Formulations
2.9
1.2
0.023
Baseline:
Hands,
dermal,
and
inhalation
=
acceptable
grades.
Bare
Hands
=
53
replicates;
Dermal
=
72
to
122
replicates;
and
Inhalation
=
85
replicates.
High
confidence
in
hand,
dermal,
and
inhalation
data.
No
protection
factor
was
needed
to
define
the
unit
exposures.

PPE:
The
same
dermal
data
are
used
as
for
baseline.
Gloved
hands
=
acceptable
grades.
Gloved
Hands
=
59
replicates.
High
confidence
in
hand
data.

Aerial
Application
0.005
0.068
N/
A
Baseline
(
Closed
Cockpit):
Hands
=
ABC
grade,
dermal
and
inhalation
=
ABC
grade.
Bare
Hands=
34
replicates,
dermal
=
24
to
48
replicates,
and
inhalation
=
23
replicates.
Medium
Groundboom
Application
0.014
0.74
0.014
Baseline:
Hand,
dermal,
and
inhalation
=
acceptable
grades.
Hands
=
29
replicates,
dermal
=
23
to
42
replicates,
and
inhalation
=
22
replicates.
High
confidence
in
hand,
dermal,
and
inhalation
data.
No
protection
factors
were
needed
to
define
the
unit
exposure
values.

PPE:
The
same
dermal
data
are
used
as
for
baseline.
Gloved
Hands
=
ABC
grades
with
21
replicates.
Medium
confidence
in
hand
data.

Flag
Aerial
Spray
Applications
0.011
0.35
0.012
Baseline:
Hands,
dermal,
and
inhalation
=
acceptable
grades.
Dermal
=
18
to
28
replicates;
hands
=
30
replicates;
and
inhalation
=
28
replicates.
High
confidence
in
dermal,
hand,
and
inhalation
data.
No
protection
factor
was
required
to
calculate
unit
exposures.

PPE:
The
same
dermal
data
are
used
as
for
baseline.
Gloved
Hand
=
acceptable
grades
with
6
replicates.
Low
confidence
in
hand
data
due
to
small
number
(
6)
of
replicates.

Notes
1.
PPE
Descriptions:
Baseline
Inhalation
­
does
not
include
respiratory
protection.
Baseline
Dermal
­
includes
long
sleeve
shirts,
long
pants,
shoes
and
socks.
Single
Layer
Dermal
­
includes
water
resistant
gloves
over
Baseline
PPE
2.
All
handler
exposure
assessments
in
this
document
are
based
on
the
"
Best
Available"
data
as
defined
by
the
PHED
SOP
for
meeting
Subdivision
U
Guidelines
(
i.
e.,
completing
exposure
assessments).
Best
available
grades
are
assigned
to
data
as
follows:
matrices
with
A
and
B
grade
data
(
i.
e.,
Acceptable
Grade
Data)
and
a
minimum
of
15
replicates;
if
not
available,
then
grades
A,
B
and
C
data
and
a
minimum
of
15
replicates;
if
not
available,
then
all
data
regardless
of
the
quality
(
i.
e.,
All
Grade
Data)
and
number
of
replicates.
High
quality
data
with
a
protection
factor
take
precedence
over
low
quality
data
with
no
protection
factor.
Generic
data
confidence
categories
are
assigned
as
follows:
High
=
grades
A
and
B
and
15
or
more
replicates
per
body
part
Medium
=
grades
A,
B,
and
C
and
15
or
more
replicates
per
body
part
Low
=
grades
A,
B,
C,
D
and
E
or
any
combination
of
grades
with
less
than
15
replicates.


PHED
grading
criteria
do
not
reflect
overall
quality
of
the
reliability
of
the
assessment.
Sources
of
the
exposure
factors
should
also
be
considered
in
the
risk
management
decision.
